Phonograph-horn neck



A. O. BARTHOLOMEW PHONOGRAPH norm max Filed Sept. 21-,- 1922 PatentedFeb. 24, 1925.

UNITED STATES PATENT OFFICE.

YPI-IONOGRAPH-HORN NECK.

T all whom it may concern:

Be it known that I, AMBROSE 0. BAR- "riiotoarnw, citizen of the UnitedStates, residing at Allentown, in the county of Lehigh and State ofPemisylvania, have invented certain new and useful Improvements inPhonograph-Horn Necks, of which the following is a specification.

This invention relates to phonographs and has special reference to ahorn connection for devices of this description.

In the construction of phonographs one important object to be attainedis the prevention of sound waves by vibration in parts of the casing ofthe machine which tend to destroy the purity of the tone and timbresought to be reproduced. Experience has shown that one of the mostfrequent causes of bad reproduction lies in the connection between thetone arm and the amplifying horn in phonographs since at this pointthere is not only a. considerable looseness which tends to produceimproper vibrations but the metallic character of this portion of thedevice itself sets up certain vibrations in the material of theconnection which produce injurious results.

One important object of the present invention is the provision of anovel character of connectibn between the tone arm and the amplifyinghorn, which connection will practically form a portion of the amplifyinghorn itself and which will prevent all improper vibrations of theconnection it self as well as to dampen or absorb any vibra tionsproduced by looseness in the connections between the connector end ofthe tone arm and amplifying horn. respectively.

A second important object of the invention is the provision of means ofnovel character to prevent setting up of such vibrations by providing aconnector of sufficient mass and lack of elasticity as to dampen andabsorb any vibrations set up therein by the sound waves passingtherethrough so that these vibrations are not transmitted to thewoodwork of the casing.

With the above and other objects in view as will be hereinafterapparent, the invention consists in general of certain novel details ofconstruction and combinations of parts hereinafter fully described,illustrated in the accompanying drawings and specifi cally claimed.

Application filed. S pt mber 21, 1922. Serial No. 589,713.

In the accompanying drawings like characters of reference indicate likeparts in the several views, and

Figure 1 a vertical median section through a phonograph showing theconnection. constructed in accordance with this invention.

Figure 2 is a section on the line 22 of Figure 1.

Figure 3 is a detail perspective view of the connection removed from thecasing.

This connection consists of a single massive block 10 of cementitiousmaterial, the material employed being preferably plaster of Paris with amixture of about 10% of ordinary cement. This material is molded into arectangular form and through the block extends a sound passage whichenters the upper end of the block as at 11 by a relatively small roundopening corresponding in size to the measure of the end of the tone arms12. The passage through the block curves downwardly and forwardly fromthis opening 11, expanding both vertically and laterally and terminatingin an opening 13 on the front side of the block which is considerablylarger than the openin 11 and is of trapezoidal form. This opening 13corresponds with the minor end of the amplifying horn 14 of thephonograph. In Figure 1 it will be seen that the phonograph casing 15 isdivided by a partition 16 into an upper chamber 17 wherein is located'aturn table 18 and tone arm 12 and a lower chamber 19 wherein is locatedthe amplifying horn 14 and motor 20. This lower chamber is divided intoa front and rear compartment by a partition 21 and the rear compartmentis provided with partitions 22 so that the block 10 can just fill thespace between these partitions, the partition 21 and back wall 23 of thephonograph. Furthermore, the height of the block is such as tocorrespond to the height of the compartment wherein it fits. With thisconstruction, it will be observed that this massive, practically nonelastic connection. absorbs without transmission to the wooden casingvibrations produced by sound waves in the passage except thosevibrations in the air which produce effective sound waves foramplification by the horn. In order to ren-. der the surface of theopening through the block smooth the walls of said opening are coated asat 24 with some material, as shellac, which will give a glassy, smoothsurface. 7

By means of this massive block it will also be noted that no vibrationsdue to the block itself will affect the air in the passage andconsequently no injurious sound waves a single curved sound passageincreased in cross sectional area from the inlet end there of to theoutlet end thereof whereby the core used in the molding operation of theblock may be readily withdrawn, said passage being trapezoidal at theoutlet end, the solid volume of the body being greatly in. excess ofthat of the opening whereby no sympathetic tones of the body due to wallvibrations will occur.

In testimony whereof I affix my signature in presence of two witnesses.V

AMBROSE O. BARTHOLOMEW'.

lVitnesses: I

ALBERT R. KLEIN, PAUL F. lVnHRLE.

